1. Field of Invention
The present invention relates to an LED controller with phase-shift dimming function; particularly, it relates to an LED controller controlling the brightness of multiple LED channels with a shifted phase. The present invention also relates to an LED phase-shift dimming circuit and an LED phase-shift dimming control method for controlling multiple LED channels.
2. Description of Related Art
FIG. 1 shows a conventional circuitry, wherein an LED controller 10 controls multiple LED channels (first LED channel CH1 to nth LED channel CHn). The LED brightness can be adjusted from the full brightness downward by an input pulse width modulation (PWM) signal 20. A duty ratio of the input PWM signal 20 determines the ON-time of the LEDs, and the higher the duty ratio is, the brighter the LEDs are. In this circuitry, all the LED channels CH1-CHn synchronously correspond to the input PWM signal 20, as shown in FIG. 2. In other words, all the LEDs turn on and off simultaneously. The drawback of this arrangement is that the brightness of the LEDs changes too sharply between ON and OFF. This reduces image quality, and it causes more interferences to the power supply circuit.
In view of the foregoing, the present invention provides an LED controller with phase-shift dimming function; the present invention also provides an LED phase-shift dimming circuit and a method thereof.